Valves can be used to control flow from one portion of an aircraft to another. For example, pneumatic valves, such as butterfly valves, may be disposed in a duct between an air source and one or more outlets to control the flow of air distributed to aircraft systems such as, for example, the environmental control system or an aircraft cabin. Typically, a butterfly valve includes a valve flowbody and a butterfly plate. The valve flowbody is disposed between two ducts (or in a portion of a single duct) and has walls defining a flow channel. The butterfly plate is rotationally mounted to the valve flowbody and is positioned in the flow channel such that a minimum clearance is formed with the walls of the valve flowbody. An actuator and a spring may be used to control the rotation of the butterfly plate.
Typically, the butterfly plate is moved between open, partially open, and closed positions. When fluid flows through the valve flowbody in a forward direction, the butterfly plate moves to the open or partially open position to allow fluid to flow through the flow channel. When in the closed position, the butterfly plate is perpendicular or near perpendicular with respect to the walls of the valve flowbody to substantially block the flow channel and inhibit fluid from flowing through the flow channel. To seal the flow channel when the butterfly plate is in the closed position, a sealing ring is included in a sealing ring annular groove formed about a periphery of the butterfly plate to engage the wall of the flowbody.
During valve operation, fluid flowing through the flow channel exerts pressure against the butterfly valve plate. As a result, the sealing ring expands radially outwards to improve sealing. However, in some instances, pressure against the butterfly valve plate may exceed a threshold value. In such case, a sealing force between the sealing ring and wall of the butterfly plate forming the sealing groove may exceed an opposing friction force between the sealing ring and plate. Hence, the sealing ring may be prevented from radially expanding, and sealing between the outer periphery of the sealing ring and the wall of the flow channel may not be as effective as desired.
Accordingly, there is a need for a butterfly valve plate sealing assembly that provides improved sealability. More specifically, there is a need for sealing between the sealing ring and the butterfly plate that remains effective even when the valve is pressurized above a threshold pressure value. In addition, it would be desirable for the sealing assembly to be relatively inexpensive to implement. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.